Hollow filament wound structures, which exhibit advantages over metal structures, such as being lighter in weight, more resistant to corrosion, stronger, and more inert, have been manufactured for several years such as:
the tubular fiber reinforced composite shaft with metallic connector sleeves mounted by a polygon surface interlock, as disclosed in U.S. Pat. No. 4,236,386, in 1980;
the tubular fiber reinforced composite shaft with metallic connector sleeves mounted by a knurl interlock, as disclosed in U.S. Pat. No. 4,238,539, in 1980;
the tubular fiber reinforced composite shaft with metallic connector sleeves mounted by a connector ring interlock, as disclosed in U.S. Pat. No. 4,238,540, in 1980;
the hollow filament wound spar structure having integral fitting for rotational hub mounting, as disclosed in U.S. Pat. No. 4,260,332, in 1981;
the tubular fiber reinforced composite shaft with metallic connector sleeves mounted by longitudinal groove interlocks, as disclosed in U.S. Pat. No. 4,265,951, in 1981; and
the wound graphite epoxy or fiberglass driveshaft joined to a metal end member as disclosed in U.S. Pat. No. 4,289,557, source in 1981.
As stated in prior patents, U.S. Pat. Nos. 4,236,386 and 4,238,539, previous proposals for mounting sleeves, i.e. end fittings, by employing adhesives or by wrapping the filament bundles around circumferential grooves on the end fitting periphery, could not be relied upon to provide a connection of the requisite strength and durability. Then the disclosures of these patents, like the other patents, illustrated and described how end fittings were positioned in the ends of hollow continuously wound filament integral structures for the transmission of torque loads.
In these prior patents there were not any direct discussions of how hollow continuously wound filament integral structures with end fittings could sustain large tension or compression loads as well as sustaining large torque loads, Moreover, there were no direct discussions of how hollow continuously wound filament integral structures could be reduced in diameter at their ends and integrally receive end fittings, which under large tension, compression, or torque loads, would remain securely in place within the hollow continuously wound filament integral structure.
There remained a need for creating hollow continuously wound filament structures having integral end fittings firmly held in place under all types of severe loads, wherein: the wound structure was completed in one overall winding operation; the diameter at the respective ends of the wound structure did not become greater and preferably remained smaller during the winding operation; and the loads carried through the respective turnaround zones of the windings were, whenever necessary, equal to the maximum loads capable of being transmitted throughout the remaining portions of the hollow continuously wound filament integral structure.